package com.github.netty.util;

import javax.servlet.annotation.WebServlet;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

public class WebServletScanner {

    public static void main(String[] args) {
        // 指定要扫描的包路径
        String packageName = "com.example.yourpackage";
        scanAndPrintWebServletAnnotations(packageName);
    }

    public static void scanAndPrintWebServletAnnotations(String packageName) {
        try {
            List<Class<?>> classes = getClasses(packageName);

            for (Class<?> clazz : classes) {
                if (clazz.isAnnotationPresent(WebServlet.class)) {
                    WebServlet webServlet = clazz.getAnnotation(WebServlet.class);
                    System.out.println("Found @WebServlet in class: " + clazz.getName());
                    System.out.println("Servlet name: " + webServlet.name());
                    System.out.println("Servlet URL patterns: " + String.join(", ", webServlet.urlPatterns()));
                }
            }
        } catch (ClassNotFoundException | IOException e) {
            e.printStackTrace();
        }
    }

    private static List<Class<?>> getClasses(String packageName) throws ClassNotFoundException, IOException {
        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
        String path = packageName.replace('.', '/');
        Enumeration<URL> resources = classLoader.getResources(path);
        List<File> dirs = new ArrayList<>();

        while (resources.hasMoreElements()) {
            URL resource = resources.nextElement();
            dirs.add(new File(resource.getFile()));
        }

        List<Class<?>> classes = new ArrayList<>();
        for (File directory : dirs) {
            classes.addAll(findClasses(directory, packageName));
        }
        return classes;
    }

    private static List<Class<?>> findClasses(File directory, String packageName) throws ClassNotFoundException {
        List<Class<?>> classes = new ArrayList<>();
        if (!directory.exists()) {
            return classes;
        }

        File[] files = directory.listFiles();
        if (files == null) {
            return classes;
        }

        for (File file : files) {
            if (file.isDirectory()) {
                assert !file.getName().contains(".");
                classes.addAll(findClasses(file, packageName + "." + file.getName()));
            } else if (file.getName().endsWith(".class")) {
                classes.add(Class.forName(packageName + '.' + file.getName().substring(0, file.getName().length() - 6)));
            }
        }
        return classes;
    }
}

